Synthesis of Solid-Solution Mn_xZn_1-xO Nanoparticles and their Electrochemical Oxidation of Furfural

Electrochemical valorization of biomass-derived substrates has become a prominent area of research due to its potential to produce value-added products from renewable feedstocks in a more sustainable way. First-row transition-metal electrodes are compelling candidates for these conversions due to their stability, abundance, and cost-effectiveness. Herein, we report on the colloidal synthesis of Mn_xZn_1-xO (x = 0.3-0.7) nanoparticles and their electrocatalytic activity toward furfural oxidation. We find that the hindrance of a MnO impurity can be achieved by leveraging the oxidation state of the Mn precursor. The Mn_xZn_1-xO composition closely follows the ratio of precursors, with all of the nanoparticles having a wurtzite structure as determined by ICP-MS and PXRD, respectively. XANES and XPS revealed the presence of Mn in different oxidation states, with the ratio of these varying based on the composition. When comparing the electrocatalytic activity of the monometallic and bimetallic oxides for furfural oxidation, a decrease in current density was observed with increasing Zn content. We find that the Mn_xZn_1-xO nanoparticles favor the formation of the 6 e^- oxidation product 5-hydroxy-2(5H)-furanone, while both monometallic oxides primarily yield CO₂ and other deeply oxidized products. These findings can contribute toward the design and synthesis of more active and selective electrocatalysts.